Protective device for grinding machines



A ril 21, 1964 w. R. BACKER PROTECTIVE DEVICE FOR GRINDING MACHINESFiled July 31 1961 2 Sheets-Sheet INVENTOR W/LL/AM I? BACK/5R ATTORNEY Aril 21, 1964 w. R. BACKER 3,129,537

PROTECTIVE DEVICE FOR GRINDING MACHINES Filed July 31, 1961 2 sheetssheet 2 L r71 7 Am 4/C' k I. I

wakvma w as 7 INVENTOR WILLIAM R. BAG/(ER ATTO RNEY United States Patent3,129,537 PRGTECTIVE DEVICE FGR GRINDING MACHINES William R. Backer,Holden, Mass, assignor to Norton Company, Worcester, Mass, a corporationof Massachusetts Filed July 31, 1961, Ser. No. 127,956 35 Claims. (Cl.51166) This invention relates to grinding machines and more especiallyto means for protecting the operator and the machine from wheelbreakage.

It is customary to mount a heavy metal hood on the wheel slide over thewheel so that if fragments of the wheel break off, or the whole wheeldisintegrates, the flying pieces will be constrained by the hood andhence will not injure the operator. With the constant improvements madein wheel construction and reinforcement, the speeds of rotation havebeen increased considerably and it is anticipated that even higherspeeds will eventually be employed. The kinetic energy in a rotatingwheel wheel increases as the square of the speed hence if a high-speedwheel breaks a large amount of energy is released and the impact of theflying fragments on the hood is extremely high. The effect of the impactis two fold in that it may not only destroy the hood itself, thus addingparts of the hood to the flying fragments of the wheel, but mayadditionally actually lift the entire slide off its ways thus seriouslydamaging the grinding machine.

The principal objects of this invention are to provide means forallaying the destructive effect of the kinetic energy released bybreaking of a high-speed grinding wheel, both for the purpose ofpreventing destruction of the wheel hood and preventing dislodgement ofany of the movable parts of the machine; to provide means which willsubstantially nullify the forces of impact without rebound; to providemeans which can be readily incorporated in an existing machine withoutextensive modification of the latter and which will not interfere withits normal operation; to provide means which can easily be renewed afterit has served its purpose; and to provide means which is of inexpensiveconstruction.

As herein illustrated, the machine is provided with a support havinghorizontally disposed ways and a wheel slide mounting a wheel and hoodtherefor, for translational movement of the wheel relative to a worksupport. The invention resides in providing deformable means arranged todissipate the kinetic energy of the fragments of the wheel as theystrike the inside surface of the hood. Since the impact forces impartedto the inside of the hood have components perpendicular to the wayssupporting the slide, the invention resides, on the one hand, indissipating the lift imparted to the wheel slide by impact of thefragments with the inside of the hood and, on the other hand, preventingdestruction of the hood itself. To nullify the lift, interlapping guidesare provided on the slide and support adjacent the ways and deformablemeans are disposed between them. For the purpose of preventingdestruction of the hood itself, additional deformable means are placedwithin the hood against its inner wall and peripherally of the wheel.The deformable means may be in the form of hollow collapsible elements,for example one or more rigid metal tubular members which Will crushwithout rebound. The tubular members may be arranged side-by-side withtheir axes lengthwise or crosswise of the guide or the inside of thehood, may be of different diameters so as to operate successively, ormay be integrated so as to operate collectively. Optionally, thedeformable member may be a rigid skeletal-like structure, deformable bycollapse of internally situated openings to dissipate the energy ofimpact. The dissipater in any of its several forms may be removablyfastened to the guides or to the inside of the hood so that when damagedit can be replaced.

It is usual to have a cover at the front of the hood andshock-dissipaters of the kind referred to above may be fastened to itsinner side to dissipate impact sustained by the cover.

The invention will now be described in greater detail with reference tothe accompanying drawings wherein:

FIG. 1 is a side elevation of a grinding machine showing a support, awheel slide mounting a wheel enclosed Within a hood, a motor, and wayson the support support ing the wheel slide for translational movement,the wheel slide, hood and cover being sectioned in part to show one formof energy dissipater means;

FIG. 2 is an elevation as seen from the right side of FIG. 1 showing theenergy dissipating means for the wheel slide and the hood, the latterbeing broken away in part to show the wheel and the energy dissipatingmeans within the hood in section;

FIG. 3 is a fragmentary elevation taken transversely of the machine atone side, showing the guideways for the wheel slide and support to muchlarger scale and the form of energy dissipater illustrated in FIGS. 1and 2;

FIG. 4 is a fragmentary elevation corresponding to FIG. 3, showinganother form of dissipater;

FIG. 5 is a fragmentary elevation longitudinally of the machine showingthe guideways at one side of the machine and another form of dissipater;

FIG. 6 is a fragmentary elevation corresponding to FIG. 3, showing stillanother form of dissipater;

FIG. 7 is a fragmentary vertical section taken through the hood at rightangles to the axis of the wheel, showing a portion of the wheel and aremovably attached dissipater similar to that shown in FIGS. 1 and 2,but with its components disposed crosswise;

FIG. 8 is a fragmentary vertical section through the hood, showing aportion of the wheel and a dissipater similar to that shown in FIG. 6,but with its components disposed crosswise;

FIG. 9 is a section through a dissipater having a rigid skeletal-likestructure containing internal openings;

FIG. 10 is a section taken on the line 1010 of FIG. 1, showing a form ofdissipater for the inside of the cover;

FIG. 11 is a graph of force versus deflection, illustrating thedissipation of energy by a single tube, a tube within a tube, and anintegrated honeycomb structure; and

FIG. 12 is a fragmentary transverse section through the hood showing amodification of the energy dissipater illustrated best in FIG. 2 inwhich the tubular members are of different diameters.

Referring to the drawings, there is shown a machine support 10 to whichthere is bolted a bearing block 12 having at its upper side t -shapedand flat ways 14 and 16 for slidably receiving a wheel slide 18. Thewheel slide 18 has mounted on it, in suitable bearings, a wheel spindle20, to one end of which is fixed a grinding or cutting wheel 22 and tothe other end of which is fixed a pulley 24. A motor M is mounted on thewheel slide and has fixed to its drive spindle a pulley 26 which isdrivably connected to the pulley 24- by belts 28 entrained about the twopulleys.

The bearing block 12 has at its opposite sides, parallel to the ways 14and 16, horizontally disposed grooves 3030, so situated as to provide,near the upper edges of the block, horizontally disposed shoulders 3232.A pair of channels 34-34 are fastened to the opposite sides of the slide18 by bolts 36 and each channel has a flange 38 at its lower edge whichprojects into the groove 30 beneath the lower shoulder 32 in spacedrelation thereto. The shoulders and channels collectively provideinterlapping guides which normally do not have contact and hence do notinterfere with the feeding movement of the slide.

In accordance with this invention, a shock-dissipating device 40 (FIGS.1, 2 and 3) is placed between each lower shoulder 32 and the flange 38of the channel. The shock-dissipator is removably secured to the flange38 by bolts 42 so that after it has served its purpose it may be removedand replaced and normally does not have contact with the shoulder 32 andhence does not interfere with translational movement of the slide on thebearing block. As herein shown, the shock-dissipator is in the form of atubular member 41 (FIG. 3) comprised of a material which will deform orcrush under high pressure without rebound, as shown in dotted lines(FIG. 3). For example, the tubular member may be comprised of metalembodying substantially no elasticity so that the application of highpressure will merely crush it. The function is to dissipate the kineticenergy released by the disintegration or breaking up of a high-speedwheel.

Alternative shock-dissipaters 40a, 40b and 400 are shown in FIGS. 4, and6. The dissipater 40a (FIG. 4) comprises an outer tube 41a and an innertube 41b fastened to the flange 38 by bolts 42. The effect of such anarrangement is that the initial impact is taken up by the outer tube upto its point of failure whereupon the inner tube takes up the balance ofthe impact thus providing for dissipating the impact in successivesteps. The tubes 41a and 41b are shown as disposed with their long axesextending lengthwise of the way however short tube sections may bedisposed transversely thereof with good results. The dissipater 4% (FIG.5) comprises tubes 41c and 41d of different diameter, disposed in spacedparallel relation to each other so as to act successively to dissipatethe energy by crushing of the tubes of larger diameter first and thoseof smaller diameter thereafter. As shown in FIG. 5 they are arrangedcrosswise of the guides. The absorber 400 (FIG. 6) is comprised of aplurality of tubes 41a, for example an integrated honeycomb structuredisposed with the long axes lengthwise of the way or transverselythereof.

Optionally, a rigid skeletal-like structure 49d (FIG. 9) may be usedwhich contains a plurality of internal openings 41 Such an element maybe made by drilling holes through a solid block or by integrating apowdered metal with a filler which can be burned out or dissolved toleave internal voids.

The wheel is enclosed within a hood 44 (FIGS. 1 and '2) fastened bybolts 46-46 to the wheel slide 18 and comprises spaced parallel sidewalls 48-48 and a peripheral wall 52. The hood is open at one side andhas a cover 54 hinged to the upper end of the opening. In accordancewith this invention, a shock-dissipater 58 is disposed within the hoodagainst the inner surface of the peripheral wall 52 about the wheel. Thedissipater 58 (FIGS. 1 and 2) comprises a sandwich of metal strips 60and 62 between which are situated a plurality of tubular members 64 towhich the strips 60 and 62 are attached in suitable fashion, for exampleby welding, brazing or the like. The tubular members 64 are similar tothe tubular members 41 employed between the shoulders 32 and flanges 38on the bearing block of the machine and are adapted to be deformed orcrushed by impact. The strip 60 may actually constitute the peripheralwall of the hood. The strip 62 should be of sufiiciently hard metal towithstand the impact of flying fragments. The unit is designed to extendall of the way around the hood, that is, from the upper end of theopening, at the forward side, rearwardly about the rear side, to thelower end of the opening.

The dissipater may, as previously described, take various forms and whentubular in makeup may be disposed with the long axes of the tubesperipherally of the wheel within the hood, as shown in FIG. 2, ortransversely thereof, as shown in FIG. 7, with tubes 64:: welded betweenthe strips 60 and 62 and fastened to the inside of the 4 hood by bolts65. Tubes of different diameter may be employed to provide for taking upthe impact in succes sive steps, as previously mentioned, by disposingthem lengthwise or crosswise of the inside of the hood, as shown in FIG.12.

In FIG. 8 there is shown a dissipater 68a in the form of a honeycomb ofintegrated tubes 69:: disposed with their axes extending crosswise ofthe hood. The honeycomb structure could be used lengthwise of the hoodin the same fashion as used with the guides (FIG. 6).

Optionally, a skeletal-like structure (FIG. 9) may be employedcomprising, for example, a block 49d containing a plurality of openings41 through it or a sintered body of high porosity.

correspondingly constructed dissipaters 58a are applied to the innerside of the cover 54. Thus, as shown in FIGS. 1 and 10, tubes 64b arewelded between metal strips 60b and 62b. Obviously, these tubes could beplaced lengthwise or crosswise of the cover and any one of thestructures related above could be substituted therefor.

The shock-dissipaters function by taking up the kinetic energy developedby the breaking wheel in such a manner as not to redirect the energy inany other direction. The dissipaters are designed, in particular, toabsorb the components of the forces of impact which are perpendicular tothe slide and which thereby tend to lift the slide off the bearing blockand those which are radial and which tend to destroy the hood. By use ofthe dissipaters, as described, the impact transmitted to the inner sideof the hood and through it to the slide is cushioned both in the hoodand on the slide by deformation or collapse of the material of which thedissipaters are compounded. FIG. 11 shows three curves x, y and 2 which,respectively, illustrate the dissipation of energy by means of a singletube, tubes of different diameter, and a honeycomb of tubesrespectively. The curves are plotted with abscissa as force and ordinateas deflection with refer ence to the maximum allowable force representedby the line a.

It is evident that when the longitudinal axes of the tubular members orstructure are placed peripherally of the wheel within the hood theyprovide added resistance to impact due to the fact that energy is usedboth in stretching the members as well as crushing them.

The present disclosure is for the purpose of illustration only and, inparticular, illustrates the broad principle of dissipating kineticenergy developed by explosion of a high'speed grinding or cutting wheelby deformation of one or more deformable elements and, moreparticularly, to the use of deformable elements which are deformable incompression. The use of deformable elements for dissipating kineticenergy deformable in tension are disclosed in my copending applicationSerial No. 128,077, filed July 3, 1961.

I claim:

1. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support and a cushion elementdisposed between the parallel portions of the guides, yieldable underpressure in response to forces tending to lift the slide from its ways.

2. In a grinding machine, a support, a. wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and deformableelements disposed between the interlapping portions of the guidesdeformable by forces tending to lift the slide relative to its ways.

3. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support and energydissipating elements disposed between the interlapping portions of theguides operable to resist lifting of the slide relative to the ways.

4. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the sup port supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and tubular elements disposed between the interlapping portions of the guides, saidelements being adapted to collapse at a pres sure sufiicient to lift theslide from its ways.

5. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and a plurality oftubes disposed between said parallel portions of the guides deformablesuccessively by forces tending to lift the slide from its ways.

6. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and a plurality oftubes of different diameter disposed between the parallel portions ofthe guides deformable successively by forces tending to lift the slideaway from its ways.

7. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and tubes ofdifferent diameter situated one within the other disposed between theparallel portions of the guide deformable successively by forces tendingto lift the slide relative to its ways.

8. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and hollow elongatemembers disposed between the parallel portions of the guides with theiraxes lengthwise thereof, said members being deformable by forces tendingto lift the slide relative to its ways.

9. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and hollow elongatemembers disposed between said parallel portions of the guides with theiraxes crosswise thereof, said members being deformable by forces tendingto lift the slide relative to its ways.

10. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and a plurality ofhollow elongate members disposed between the "guides with their axescrosswise thereof, said hollow members being deformable successivelyunder pressure tending to lift the slide away from its ways.

11. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, a plurality ofhollow members disposed between the guides with their axes lengthwise ofthe ways operable collectively, by deformation, to dissipate the energyof impact.

12. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational move- 6 ment relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and a plurality ofintegrated hollow members disposed between the parallel portions of theguide operable collectively, by deformation, to dissipate the energy ofimpact.

13. In a grinding machine, a support, a wheel slide mounting a Wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and a plurality ofintegrated hollow members disposed between the interlapping portions ofthe guide with their axes lengthwise thereof, operable collectively, bydeformation, to oppose lifting of the slide away from its ways.

14. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the sup port supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and a plurality ofintegrated hollow members disposed between the parallel portions of theguides crosswise thereof which collectively operate, by deformation, tooppose lifting of the slide away from its ways.

15. In a grinding machine, a support, a wheel slide mounting a wheel anda hood therefor, ways on the support supporting the wheel slide fortranslational movement relative to the work, spaced parallelinterlapping guides on the wheel slide and support, and energydissipating means disposed between the interlapping portions of theguides comprising a sandwich of a pair of strips and a plurality oftubular members disposed between them and attached thereto.

16. In a grinding machine, a support having horizontally disposed waysand subjacent thereto horizontally disposed shoulders, a wheel slidemounting a wheel and a hood, resting on the ways, anchoring elementsfixed to the slide having portions underlying the shoulders, and energydissipating means disposed between the shoulders and the portions of theanchoring elements underlying the shoulders.

17. In a grinding machine, a support having horizontally disposed waysand subjacent thereto horizontally disposed recesses providing undercutshoulders paralleling the ways, an anchoring element fastened to theslide at each side, each anchoring element having a flange projectinginto the groove at that side beneath the shoulder, but being spaceddownwardly therefrom, and cushion elements disposed in the spacesbetween the flanges and shoulders, said cushion elements being fastenedto the flanges.

18. In a grinding machine, a wheel slide mounting a wheel and a hoodtherefor, said slide supporting the wheel for translational movementrelative to the work, said hood enclosing the wheel, and a plurality ofelongated hollow permanently deformable members of different diametersdisposed about the inside of the hood with their axes disposedcircumferentially of the wheel sequentially effective by permanentdeformation thereof to dissipate energy released when a wheel breaks.

19. In a grinding machine, a wheel slide mounting a wheel and a hoodtherefor, said slide supporting the wheel for translational movementrelative to the work and said hood enclosing the wheel, and anintegrated plurality of elongated hollow permanently deformable membersdisposed about the inside of the hood with their axes disposed crosswiseof the periphery of the wheel effective by permanent deformation thereofto dissipate energy released when a wheel breaks.

20. An expendable energy dissipater comprising a plurality of hollowtubular members of dilferent diameters all open to the atmosphere anddisposed side-by-side in spaced parallel relation between a pair of flatstrips and secured thereto, operable by permanent deformation of thetubular members in response to high impact force components normal tothe flat strips.

21. An expendable energy dissipater for a machine tool having a highspeed cutting tool comprising a composite permanently deformableskeletal structure partially enclosing a plurality of internal airspaces and shaped to be disposed between spaced relatively movableelements of a machine tool without restricting the relative movement ofthe spaced machine tool elements under normal operating conditions, andreleasable means for securing said skeletal structure to one of thespaced machine tool elements so that relative movement of one machinetool element toward the other machine tool element in the event ofcutting tool failure is cushioned by permanent deformation of saidskeletal structure.

22. In a grinding machine, a Wheel slide mounting a wheel and a hoodtherefor, said slide supporting the wheel for translational movementrelative to the work and said hood enclosing the wheel, and an elongatedenergy dissipating element disposed around the circumference of thewheel and secured fixedly to the inner surface of the hood, said energydissipating element including permanently deformable tubular elementseverywhere adjacent to the inner surface of the hood, and a continuousliner disposed against the inner sides of the tubular elements forreceiving the impact of the fragments of a broken wheel and fordissipating the energy of impact by permanent deformation of the tubularelements.

23. In a grinding machine, a wheel slide mounting a wheel and a hoodtherefor, said slide supporting the wheel for translational movementrelative to the work and said hood enclosing the wheel, and an energydissipating element disposed peripherally of the wheel within the hood,said energy dissipating element comprising a plurality of permanentlydeformable tubular elements fixedly secured to the inner surface of thehood, and a continuous liner strip attached to the inner sides of thetubular elements.

24. In a grinding machine, a wheel slide mounting a wheel and a circularhood therefor, said slide supporting the wheel for translationalmovement relative to the work and said hood enclosing the wheel, acircularly curved sandwich member disposed within the hood against itsinner surface peripherally of the wheel, said member being comprised oftwo strips of sheet metal attached to the opposite sides of a pluralityof permanently deformable metal tubes disposed therebetween, and meansfixedly securing said member to said hood.

25. In a grinding machine, a wheel slide mounting a wheel and a rigidhood therefor, said slide supporting the wheel for translationalmovement relative to the work and said hood having a front openinggiving access to the wheel and a rigid hinged cover partially closingthe upper part of the opening, and a permanently deformable energydissipating device substantially coextensive with and fastened to theinside surface of the cover.

26. In a grinding machine, a wheel slide mounting a grinding wheel and ahood therefor, ways supporting the Wheel slide for translationalmovement relative to the work to be ground, said hood enclosing thegrinding wheel to constrain wheel fragments released if the grindingwheel breaks, and including solid deformable means fixedly secured tothe inside surface of the hood operable, by permanent deformation ofsaid means due to the impact of the wheel fragments against said meansconstrained by the hood, to dissipate the energy of the impact.

27. In a grinding machine, a wheel slide mounting a grinding wheel and ahood therefor, ways supporting the wheel slide for translationalmovement relative to the work to be ground, said hood enclosing thegrinding wheel to constrain wheel fragments released if the grindingwheel breaks and including a plurality of solid deformable means fixedlysecured against the inside surface of the hood and operablesuccessively, by permanent deformation of said means due to the impactof the fragments against said means constrained by the inside surface ofthe hood, to dissipate the energy of the impact.

28. In a grinding machine, a wheel slide mounting a grinding wheel and ahood therefor, ways supporting the wheel slide for translationalmovement relative to the Work to be ground, said hood enclosing thegrinding wheel to constrain wheel fragments released if the grind ingWheel breaks and including a plurality of solid deformable means fixedlysecured to the inside surface of said ho'od operable collectively, bypermanent deformation due to the impact of wheel fragments against saidmeans constrained by the inside surface of the hood, to dissipate theenergy of impact.

29. In a grinding machine, a wheel slide mounting a grinding wheel and ahood therefor, ways supporting the wheel slide for translationalmovement relative to the work to be ground, said hood enclosing thegrinding wheel and being adapted to constrain wheel fragments releasedin the event the grinding wheel breaks, the impact of some of whichimpart forces which tend to lift the wheel slide from its ways, andsolid deformable means fixedly secured to the inside of said hoodoperable by permanent deformation of said means in response to suchimpact forces to dissipate said energy of impact tending to lift thewheel slide from its ways.

30. In a grinding machine, a wheel slide mounting a grinding wheel and ahood therefor, said slide supporting the grinding wheel fortranslational movement relative to the work, said hood enclosing thegrinding wheel, and a plurality of elongated hollow permanentlydeformable members fixedly secured to the inside of the hood with theiraxes disposed circumferentially of the grinding wheel effective incombination with the hood by permanent deformation of said members todissipate energy released when the grinding wheel breaks.

31. In a grinding machine, a wheel slide mounting a grinding wheel and ahood therefor, said slide supporting the grinding wheel fortranslational movement relative to the work, said hood enclosing thegrinding wheel, and a plurality of elongated hollow permanentlydeformable members fixedly secured to the inside of the hood with theiraxes disposed transversely of the periphery of the grinding wheeleffective in combination with the hood by permanent deformation of saidmembers to dissipate energy released when a grinding wheel breaks.

32. In a grinding machine, a wheel slide mounting a wheel and a hoodtherefor, said slide supporting the wheel for translational movementrelative to the work and said hood enclosing the wheel, and a pluralityof elongated hollow permanently deformable members of differentdiameters fixedly secured to the inside of the hood with their axesdisposed crosswise of the periphery of the wheel sequentially effectiveby permanent deformation of said members to dissipate energy reelasedwhen a wheel breaks.

33. In a grinding machine, a wheel slide mounting a wheel and a hoodtherefor, said slide supporting the wheel for translational movementrelative to the work and said hood enclosing the wheel, and anintegrated plurality of elongated hollow permanently deformable membersfixedly secured to the inside of the hood with their axes disposedcircurnferentally of the wheel effective by permanent deformation ofsaid members to dissipate energy released when a wheel breaks.

34. An expendable emergency energy dissipater for a machine tool havinga high speed cutting tool comprising a hollow skeletal structure made ofsolid material resistant to permanent deformation and shaped to fitbetween and fixedly secured in engagement with the surface of one ofopposed spaced relatively more rigid elements of a machine tool subjectto abrupt mutual engagement in the event of cutting tool breakage sothat energy released by cutting tool breakage is dissipated by permanentdeformation of said skeletal structure.

35. An expendable emergency energy dissipater for a 10 machine toolhaving a high speed cutting tool comprising References Cited in the fileof this patent a hollow skeletal structure made of solid materialresistant UNITED STATES PATENTS to permanent deformation and shaped tofit between spaced elements of a machine tool subject to abrupt mutualen- 369'796 Kelly, Sept" 1887 gagement in the event of cutting toolbreakage, said 5 11286518 Brasslu 1918 hollow skeletal structure beingprovided with elongated 1,447,996 Muehlhauser 1923 internal openingstherethrough disposed generally parallel FOREIGN PATENTS to the surfaceof at least one of the machine tool ele- 57 381 Germany July 2 1891ments adjoining said skeletal structure, so that energy 181:314Switzerland Mar 2:1936

released by cutting tool breakage is dissipated by perma- 10 nentdeformation of said skeletal structure.

1. IN A GRINDING MACHINE, A SUPPORT, A WHEEL SLIDE MOUNTING A WHEEL ANDA HOOD THEREFOR, WAYS ON THE SUPPORT SUPPORTING THE WHEEL SLIDE FORTRANSLATIONAL MOVEMENT RELATIVE TO THE WORK, SPACED PARALLELINTERLAPPING GUIDES ON THE WHEEL SLIDE AND SUPPORT AND A CUSHION ELEMENTDISPOSED BETWEEN THE PARALLEL PORTIONS OF THE GUIDES, YIELDABLE UNDERPRESSURE IN RESPONSE TO FORCES TENDING TO LIFT THE SLIDE FROM ITS WAYS.